An organic Light Emitting Diode (OLED), as an organic thin film electroluminescent device, has the advantages of simple fabrication process, low cost, high luminous efficiency, ease of formation of a flexible structure, and the like. Hence, the display technology of the organic light emitting diode becomes a hot spot to be researched and developed.
An organic light emitting diode display device includes a plurality of pixel units, each of the pixel units consists of a plurality of sub-pixel units being adjacent to each other and emitting light of different colors, and each of the sub-pixel units being provided with one organic light emitting diode therein. The light emitting intensity of organic light emitting diodes may be controlled by controlling the current of each of the organic light emitting diodes by a Thin Film Transistor (TFT) array, so as to realize displaying. Light emitted from the sub-pixel units of each pixel unit is mixed to form light to be emitted from this pixel unit. There may be many modes for the configuration of colors (i.e., the color of the color filter) of the sub-pixel units, for example, RGB (red, green and blue) mode (i.e., one red sub-pixel unit, one green sub-pixel unit and one blue sub-pixel unit form one pixel unit), RGBW (red, green, blue and white) mode, or RGBY (red, green, blue and yellow) mode.
A white Organic Light Emitting Diode (WOLED), due to being a mature technology and having high luminous efficiency, has been widely applied in the organic light emitting diode display device.
As shown in FIG. 1, in the prior art, an organic light emitting display device includes a thin film transistor array substrate 1, a color filter layer 3 (for example, including color filters R, G and B in FIG. 1) provided on the thin film transistor array substrate 1, a planarization layer 2 provided on the color filter layer 3, and an organic light emitting unit 11 provided on the planarization layer 2.
The organic light emitting unit 11 includes a plurality of sub-pixel units 12 divided by pixel defining layers 5, and each of the sub-pixel units 12 includes an anode 4 close to the thin film transistor array substrate 1 and a cathode 7 away from the thin film transistor array substrate 1 and an organic light emitting layer 6 between the anode 4 and the cathode 7. The anode 4 of each of the sub-pixel units 12 is controlled individually by one thin film transistor, and the anode 4 is connected to the thin film transistor through a via. As the cross-section is not at the via, the via is not shown in FIG. 1. All cathodes 7 of the whole organic light emitting unit 11 are usually integrated.
An encapsulating layer 8 may be further provided on the cathodes 7 to encapsulate the organic light emitting display device.
The light emitting process of the organic light emitting display device as described above is as follows: by controlling the current intensity of the anode 4 of each of the sub-pixel units 12 in a pixel unit, the organic light emitting layers 6 in the sub-pixel units 12 emit white light of different brightness; and, those white light passes through the corresponding color filters R, G and B to form light of different colors. The light of different colors is mixed to form light to be emitted by this pixel unit.
It should be understood that the above-mentioned color filter layer 3 may be omitted if the organic light emitting layer itself emits light of three primary colors (for example, R, G and B). In this case, the organic light emitting unit 11 is directly fabricated on the thin film transistor array substrate 1.
However, in the prior art, although part of moisture in the thin film transistor array substrate 1 and the color filter layer 3 is removed by roasting during fabrication, it is unable to remove the moisture completely. Therefore, there is moisture escape during the use of the organic light emitting display device. The organic light emitting diode is so extremely sensitive to moisture that even a thimbleful of moisture escape may directly influence the service life of the organic light emitting diode, and thus influence the service life of the display panel.